Ancient Ancestors

Monitoring of keywords and phrases, used by visitors searching my websites, has revealed that I had neglected to include Cormorants in this feature. This has now been rectified. Further revision, mainly of Galliformes, on 22nd April 2013.

Monitoring of visits to website pages suggests quite a strong interest in the following reviews which can be seen in Birds by Common Name Groups:-

• Early Birds – Ostrich through to Curassows.
• Game birds – Takahe through to New World Quail.
• Waterfowl – Screamers and Geese.
• Sea and Ocean birds - Penguins and Albatross.
• Inland Water birds – Loons, Grebes.

I am currently reviewing information about the evolution of the earliest of our modern birds and thought the following summary might be of interest.



The ancestors of the birds we know today co-existed with the dinosaurs. Perhaps the hardest thing to grasp, if you want to see the evolution of birds in a meaningful perspective, is the timescale involved. The evolution of birds began about 150 million years ago (mya) whereas human beings have been around for less than 1 million years.

Some of the birds we can still see now are descendents of genera which evolved about 100 mya so if you want to understand birds it is necessary to get some feel for how, and in what circumstances, they evolved.

Evolutionary timetable up to 65 mya.

In the relatively few years that I have been studying birds, evolutionary evidence from fossils has been augmented by DNA and other studies. Ornithologists appear to be in reasonable agreement on the timing of evolutionary events listed in the table below. Slight differences which appear in the time of evolution for various birds in the text which follows the table reflect the views expressed in various studies.

230 Flying reptiles - Pterosaurs evolved – extinction in K/T event 65 mya
150 Archaeopteryx evolved, now extinct
130 Enantiornithes evolved – extinction in K/T event 65 mya
103 Hesperornithiformes – extinction in K/T event 65 mya
92 Ichthyornithiformes – extinction prior to K/T event about 82 mya
89 Neornithes evolved
88 Palaeognaths – Ancestors of Tinamous & flightless Ratites, Ostrich, Rhea
88 Neognaths – Galloansers and Neoaves.
82 Neoaves – all other birds except Palaeognaths and Galloansers
77 Galloanseres – common ancestor of Galliformes and Anseriformes
77 Galliformes – Cracids, Megapodes, Phasianids etc
72 Anseriformes – Anhimidae, Anseranatidae, Anatidae
72 Modern Sea-bird lineages diverging from Neoaves
71 Common ancestor of Penguins and Albatross evolved
65 K/T event.

One thing I should say about such lists is that they inevitably suggest that things have happened in a structured, ordered and sequential manner and may imply relationships which don’t exist. It is better to see events as being snapshots of various, at present unrelated parts, of an evolutionary tree. Evolution of birds did not just happen once it has happened many times in many different parts of the world.

Pterosaurs - are the earliest vertebrates known to have evolved the ability to fly. Their wings were formed by a membrane covered with hairy filaments. Early species had long, toothed jaws and long tails, while later forms had a reduced tail, and some lacked teeth. They existed from 220 mya until extinction in K/T event 65 mya

Archaeopteryx - had a bony tail, clawed fingers, teeth in its beak and feathers on its body. It is considered to be a genus which is transitional between hairy / feathered dinosaurs and birds.

Enantiornithes - were long-legged, aquatic birds which evolved into environments where fish were readily available and provided food for Hesperornithiformes and Ichthyornithiformes.

Hesperornithiformes - were long bodied with their feet placed well to the rear of the body reminiscent of Loons and Grebes.

Ichthyornithiformes - were Gull or Tern-like birds with a well developed keel to the breastbone which anchored flight muscle.

Neornithes- are the most recent common ancestor of all living birds. They are divided into Palaeognathae and Neognathae, containing all other birds. It is generally agreed that the Neornithes evolved in the Cretaceous Period and that the split between the Palaeognathae and Neognathae, followed by the split between Galloanserae and the other Neognathae, occurred before the K/T extinction event.

Palaeognaths – refers to the skeletal anatomy of the palate, which is described as more primitive and reptilian than that in other birds. These birds are considered to be the most primitive or basal of our living birds. Tinamous, which are weak fliers, are the sister group to the flightless Ratites like Ostrich, Rhea etc.

Neoaves - is a group that consists of all modern birds (Neornithes) with the exception of Palaeognathae and Galloanserae.

Galloanserae - is an avian taxon bracketing the common ancestor of Anseriformes and Galliformes and all its descendants.

Galliformes – a few fragmentary fossils of putative Galliformes from the Cretaceous period have been found. The most interesting is Austinornis which was quite certainly closely related to the Galliformes, but whether it was a part of these or belongs elsewhere in the little-known Galliform branch of Galloanserae is not clear. A fossil from the Late Cretaceous (90 mya) found in Argentina, which resembles the more basal parts of this lineage, is a more likely Galliformes candidate.

This order contains five families:-Megapodiidae, Cracidae (including Chachalacas and Curassows), Numididae (Guineafowl), Odontophoridae (New World Quail) and Phasianidae (Pheasants etc). The Megapodes, are primitive mound nesters, and the Horned Guan in family Cracidae, tend to be regarded as very ancient species.

Modern-type Galliformes are known from about 45 mya and these have eventually completely replaced their older relatives. Since the earliest living representatives apparently belong to the Phasianidae, which is the youngest family of Galliformes, representatives of other Galliformes families, which are now extinct must be at least of Early Eocene (55 mya) origin but might even be as old as the Late Cretaceous (65 mya).

Anseriformes (Waterfowl) - the oldest known waterfowl, Vegavis iaai, dates from about 70 mya. The order currently contains three families:-Anhimidae (Screamers), Anseranatidae (Magpie Goose) and Anatidae (Ducks, Geese and Swans). All species in the order are highly adapted for an aquatic existence at the water surface.

Modern Sea-birds – it is likely that some of the orders of birds we know today – Sphenisciformes, Gaviiformes and Procellariiformes, had begun to evolve in some form prior to the K/T event.

K/T event – a giant asteroid or comet impacted the earth. The impact, and the environmental repercussions, resulted in a global mass extinction of animals and plants.

People generally regard Archaeopteryx as the ancestor of all other birds. Although Archaeopteryx and the various Enantiornithes were clearly precursors of our modern birds they were not their direct ancestors. They appear to have been wiped out by the K/T event.

Birds which survived the K/T event.

Studies suggest that birds almost certainly evolved about 90 mya from theropod dinosaurs. Those which survived the K/T event and continued to evolve further are listed below:-

Palaeognaths plus the Galliformes and Anseriformes.

These birds are plant eaters both on land and in the water and these foods were already available 90 mya when the ancestors of these birds were evolving.

• Tinamous, 80 and Ratites, Ostrich, 75, Rhea 65. (Kiwi and Emu evolved about 50 mya).
• Galliformes, Game Birds, Cracids, 80. (Chicken, Pheasant, Quail etc evolved about 42 mya).
• Anseriformes,Vegavis 70. (Screamers, Magpie Goose).

Sea-birds - Sphenisciformes, Gaviiformes and Procellariiformes.

All these birds (and indeed all other birds) fall into the Neoaves category. This group are fish eaters and fish were certainly available in the seas and oceans when these birds were evolving.


Millions of years ago these birds could fly. Eventually flying became unnecessary; they didn’t have any land-bound enemies that would make fast escape by air necessary, so they spent most of their time in the waters of the Southern Hemisphere.

These birds shared a common ancestor with the Albatross 71 mya. They became flightless with their wings becoming flippers to propel them through the sea. Their feet are so far back on the body that they stand upright on land.

Currently the oldest known fossil Penguin species is Waimanu manneringi, which lived about 62 mya. While they were not as well-adapted to aquatic life as modern Penguins, Waimanu were already flightless, with short wings adapted for deep diving. They swam on the surface, mainly using their feet, but their wings were already adapting to swimming underwater.

By 40 mya the earlier versions were becoming extinct because they were unable to compete with other fish eaters. At about this time genus Aptenodytes the King and Emperor Penguins diverged and became basal to the group which are our modern Penguins. Further divergences resulted in new species in the period 34 to 25 mya and again 5 mya. Penguins are only found in the Southern Hemisphere on the southern coasts of Australia, New Zealand, South Africa and South America and Antarctica.


The Loons are often considered to be the most ancient of the Northern Hemisphere bird families. This idea perhaps reflects the perceived similarity of shape and habits between Loons and the, extinct Hesperornithiformes. Some evidence suggests that the ancestors of Loons evolved about 70 to 80 mya. Modern Loons are only known with certainty since the Eocene period (55 to 34 mya).

Other Aquatic birds.

Other birds associated with the aquatic environment are thought to have evolved quite early but I have not found firm evidence as regards the time of their evolution.


The Grebes were at first believed to be related to the Loons which are also foot-propelled diving birds, and both families were once classified together under the order Colymbiformes. This was determined to be an example of convergent evolution by selective forces encountered by unrelated birds sharing the same lifestyle at different times and in different habitat. True Grebes appear in the fossil record in the Late Oligocene or Early Miocene, around 23–25 mya.


Recent molecular studies and morphological evidence strongly supports a relationship between Flamingos and Grebes. Flamingos are well attested in the fossil record, with the first unequivocal member of the extant family Phoenicopteridae, El known from the Late Eocene. The fossil Palaelodids can be considered evolutionarily and ecologically, intermediate between Flamingos and Grebes.


Cormorants appear to be an ancient group, with ancestors reaching back to the time of the dinosaurs. Fossilised remains suggest that these ancestors may date back as far as 66 to 70 mya.

They have exploited many different aquatic environments but they tend to favour coastal or inland waters. They tend to avoid the oceans. They range around the world, except for the central Pacific islands, but they are most diverse in the regions bordering the Indian Ocean.

It appears likely that the Cormorant ancestors were already a distinct group undergoing evolutionary radiation about 65 mya. It has been suggested that the collision and joining of the Indian tectonic plate with the Asian plate about 25 mya was the trigger which caused the modern Cormorants we know today to diverge from the ancestral line.

Some evidence suggests that the ancestral birds originally favoured fresh waters so it has been postulated that "modern" cormorants were species from Eastern or Southern Asia, possibly living in freshwater habitat, which dispersed due to the above tectonic events.

Other Neoaves.


The Palaeocene genera Berruornis and Ogygoptynx show that owls were already present as a distinct lineage some 60–57 mya, and possibly even some 5 million years earlier, at the extinction of the non-avian dinosaurs.


So far I have found little information about the evolution of Parrots. There is a vague suggestion that they were evolving 100 mya and a more positive comment that species now found in South America diverged from an Australian group 76 mya. What gives this a little more credence is that fleshy fruits were becoming available in the closed forest systems of Australia so that food which Parrots prefer was certainly becoming available.


Ground Hornbills.

Some evidence suggests that these birds were evolving about 80 mya. The physical appearance of these birds certainly suggests their primitive origins. This photograph of the Southern Ground Hornbill (right) was taken in Kenya. These birds are certainly carnivores now and small mammals would have been available.


These birds were long thought to have evolved some time later but evidence now suggests that the New Zealand Wrens and the Sub-Oscine and Oscine groups were evolving 80 mya. They would have been insect eaters and this food was also readily available.

Other birds.

The Hoatzin, Cuckoos, Rollers, Turacos, Frogmouths and other nocturnal hunters, Pigeons and Sandgrouse have all been suggested as possibly evolving at about the time of the K/T event but I have not found any evidence to support this view. I also expected to find evidence of early ancestors of Birds of Prey but they appear to have evolved well after the K/T event.

Concluding comments.

The following are the most ancient of our living birds:-

• Tinamous - 49 species, almost all in South America.
• Ostrich and Rhea – Emu and Kiwi evolved later.
• Game Birds – Galliformes – Megapodes, Guans, others?
• Screamers and Magpie Goose.
• Penguins - and possibly Albatross, Loons, Grebe, Flamingos and Cormorants.
• Owls.
• Parrots.
• Ground Hornbills.
• New Zealand Wren.
• Early Sub-Oscines and Oscines.

All these birds appear to have evolved in the period 90 to 65 mya, subsequently surviving the K/T event in some form or other.